Question

The curator of the art museum, _____ gave a speech last night, will be attending tonight's ceremonies, as well.

A:which
B:who
C:that

Answer 1

B.) Who

Step-by-step explanation:

The curator of the art museum, who gave a speech last night, will be attending tonight's ceremonies, as well.

The term "that" is a less formal way to put it. And using the term "which" does not make grammatical sense, so your best choice would be "who".